Time delay relay



Feb. 25, 1941.. C, LARSON 2,232,878

TIME DELAY RELAY Filed May 5, 1939 Patented Feb. 25, 1941 PATENT OFFICE I mm: 4 m cm! may cm a. umn. mm. but. aalignor to m Adlake Company, a corporation of Illinois Application am a, 1m, Serial No. 211.540

' 4 cum. (on. 20041) This invention relates to mercury switch relays, and in order to understand the objects 0! the invention, it is necessary to define certain terms that will be used:

Normal operate time is the time required to produce a change in the electrical circuit through the switch when the relay winding is suddenly closed while all parts of the switch ,are lying in stable equilibrium.

Norma. release time is the time required to produce a change in the electrical circuit'through the switch when the relay winding is suddenly opened while all parts oithe switch are lying in stable equilibrium.

Normal operate recycling time is the minimum period during which the relay winding must be permitted to remainopen in order that the normal operate-time is obtainable when the relay winding is suddenly closed. Usually, though not always, the normal operate recycling time is the same as the time required tor the switch elements to reach stable equilibrium alter the relay winding has been opened= Normal release recycling time is the minimum period during which the relay winding must be permitted to remain closed in order that the i102 incl release time is obtainable when the rel y winding is suddenly opened. Usually, though not always, the normal release recycling time is the scene as the time required tor the switch ciemente to reach stable equilibrium after the relay whiding hep closed.

enact: cpmoic reset reiers to the ability oi a civitm to give normal operate time without ra release reset relera to the ability cl a switch to give normal release time without requir ing a particular time interval to precede the opening of the relay winding.

@bviously in writing commerecial specifications for relays oi this kind, minimum and maximum values are often given ior operate and release ime, these values representing time intervals h must be met regardless of the reiative'poeioi the switch parts (i. e. in stable equilibrior notl at the instant that the condition of the electrical circuit through the relay winding is changed. The minimum valuesare usually specified to prevent an immediaw change in cizrcondition in the event of cub-normal recycling conditions, and the maximum values are usually given to hold the operation of the relay to reasonable cycles or to meet some other special operating condition.

With the above definitions in mind, the principal object of the invention is to provide a mercury switch relay oi the slow make, slow breaktype characterized by its ability to meet specifications for minimum release time in the event of ized further by the fact that the relay switch has quick release react properties.

A iurther object is to accomplish the above result by the use oi two cooperating and inter+ dependent time delay elements.

Father and other objects and advantages will become apparent as the disclosure proceeds and the description is read inconjunction with the accompanying drawing, in which Fig. 1 la a vertical sectional view of a relay embodying the principles of this invention, the switch parts being shown in the position which they assume immediately after the relay coil has been lie-energized; and

Pig. 2 is a view similar to Fig. 1 but showing the switch parts in the position which they assume immediately after the relay coil has been deenergized tor a period corresponding to normal operate recycling time and then suddenly energized.

A preferred form of the invention has been illustrated in the drawing and will be hereinafter described in compliance with fiec. e888 oi the Revised Statutes, but the invention is not limited to the specific disclosure containedher ein and the appended claims should he conotrued as broadly as the prior art will permit.

There are some electricalcircuits in winch a relay used to control the operation of other electrical equipment. must be incapable of closing the contacts of the relay switch until after c given time interval has elapcccl following the cleenergiaation of the relay coil. The relay of thin havention may he used satisiactorily to ll such ment type is mounted in operative relation to the coil II and comprises a switch envelope it oi low expansion hero-silicate glass through the base oi. whichiead-ln wires it and id oi. molybdenum, tungsten, or the like are pinch-sealed. A glass sleeve i'l surrounds the lead-in it to a point adjacent its upper cnd leaving an exposed electrode portion il projecting above the sleeve H. A ceramic cup i! is bonded, preferably by msion, to the sleeve H to retain a pool of mercury in contact with the electrode i8.

A glass thimble, :enerally designated 20 is teleacoped over the upp r p rtion oi the lead-in i0 I v N u 8 V & N U N 0 I 3:, m M m w a 4 u E u WMWMWW wmwmmwmw m mmmmwmmmm mm MM mwmmmmmmmmmmmmm a n a um m a w m m m m mmmhr m t m m m wm m MP0,. um MW mww mm w w m m m m mmm huw mg m w u u W ,mwfimmm. mmwmmmwmmmmmmm M w ma a @mm wm mmmmm u rfiwww m vmw m m mm m mwmflm rmxrm w WW m y W m m m wm mw mmm m m mm m m m T. mmm m a mm w mm wm mfi mhEWW JME fifN W m nW E m r wam:iuwmfimxmmmmmmmmwmmm mmmm v w 7. a b b? M u mm mwm m mwm mm mm m wmm m WWW M WM mmmmmmmm mm w mammal Wmwfi 3 My MW m M m mmmmmmwmmm E is m i ffilmmmmmm M r m u wmvm ah 2. g m mmwmm W W mm mm mm m x mm mm a m m M mm mm m mm mmmm m m a w .f 1m m m m m m mm m m gaw am m mm m y m v m mmmuwmmmmmmmmmm :Wmmfi wmwmm uwmmmw mmmmm mmmmmmmmmmm u n a a u u n u n in which the mercury level within. the thimble II has, pursuant to energization of the coil l0, fallen to a position just below the top of the cup I! (and consequently broken the circuit through the switch) and immediately after the circuit has been broken, the coil ID has been suddenly do energized. The quick drop of the plunger 28 in such circumstances would cause the mercury within the thimble '20 to surge upwardly and produce a substantially instantaneous closing of the circuit through the electrodes 18 and 22 and without the elapse oi the prescribed minimum release time. It is to avoid this condition that the relay of this invention is designed to give minimum release time in spite of sub-normal release recycling time.

It is obvious from the hypothetical condition set forth above, that if the opening 25 is placed, as shown in Figs. 1 and 2, the de-energization of the coil I'll without the elapse 01 normal release recycling time, cannot result in causing the switch to close its contacts before the elapse oi minimum release time, and in the particular embodiment of the invention disclosed, the switch contact cannot be closed at any time in less than. normal release time.

It should be noted that in the particular relay shown, the specifications permit a subnormal operate time of zero, for it can readily be seen that ii the coil II is energized immediately after the circuit between the electrodes I8 and?! has been closed, the circuit will at once be re-opened.

By way or specific example, but by no means limiting the scope of this invention, let us suppose that the relay specifications call Ior 45 seconds normal operate time, two minutes normal release time, and two seconds minimum release time in case of sub-normal release recycling'time, the switch of this invention would fill the specifications by selecting the plug 28 so that it would of itself produce, let us say, eight seconds of time delay (to bring about stable equilibrium assuming the fixed thimble 20 were omitted) and by choosing the plug 24 so that it would produce a $5 second time delay in permitting the mercury column to tall from the level 30 (Fig. 2), to the point where it breaks the circuit through the switch.

What I claim is:

1. In a mercury switch relay having a predetermined minimum release time, the combination of a relay coil, a switch of the slow make, slow break type associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow dispiacer responsive to the coil for shifting the mercury level, a time delay element carried by displacer and arranged so that downward movement of the dlsplacer in the mercury fill cause;- the mercury to slowly rise in the displacer at a rate proportionate to the action 01. the time delay element, while upward movement or the displace:- causes the mercury to move quickly in a direction that tends to empty the displacer of mercury, and a second time delay element comprising a thimble provided at the top with a restricted gas opening and at the side with an opening for the tree passage of mercury, said two time delay elements being so correlated that for normal recycling time, the normal operate and release times are obtained, but for sub-normal release recycling time, the predetermined minimum release time is efiected.

2. In a mercury switch relay, the combination of a relay coil, a switch oi! the slow make type associated with the coil, said'switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow displacer responsive to the coil tor shitting the mercury level, a

time delay element carried by the displacer and arranged so that downward movement of the displacer in the mercury fill causes the mercury to slowly rise in the displacer at a rate proportionate to the action of the time delay element, while upward movement of the displacer causes the mercury to move quickly in a direction that tends to empty the displacer of mercury, and a second time delay element including portions rigidly telescoped over one o! the electrodes and arranged with respect to the displacer and other switch elements so that downward movement of the displacer causes the switch electrodes to open at once, it not already opened, and be thereafter incapable of closing until after the lapse oi a predetermined minimum period of time, regardless oi. subsequent movements of the displacer.

3. In a mercury switch relay, the combination or a relay coil, a switch 01' the slow make type associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow displacer responsive to the coil tor shitting the mercury level, a time delay element including portions rigidly telescoped over one of the electrodes, said displacer being substantially closed at its upper end to form a gas pocket therewithin adapted to contain a predetermined minimum volume of gas and being constructed and arranged so that the downward movement of the displacer causes the gas trapped within the displacer to force mercury downwardly to open at once, it not already open, the switch electrodes, whereatter said time delay element prevents the electrodes from being bridged with'mercury until after the lapse of a pre-determined'minimum period or time, said displaceson its upward stroke being raised a distance suflicient to place the interior of the displacer in gaseous communication with the exterior thereof to assure the presence of the predetermined minimum volume o! gas within the gas pocket that is effective for iorcing mercury downwardly to open the electrodes on the next downward stroke 01 the displacer.

4. In a mercury switch relay having prescribed operating characteristics, the combination of a relay coil, a switch associated with the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow ,displacer responsive to the coil for shifting the mercury level, and cooperating time delay elements associated with one of said electrodes to delay the movement of mercury with relation to said electrode upon a change in the condition 01' the electrical circuit through the coil, one or said time delay elements comprising a gas leakage device associated with the displacer and the other comprising a relatively fixed gas leakage device associated with said one electrode, and means including at least one of said time delay elements for insuring that the switch shall possess minimum release time characteristics.

, CARL H. LARSON. 

